United ESTA and the Visa Waiver Program

Key parameters
Limit	90 days
Period / Window	Per visit
Counting	Any part of a day
Additional requirements	ESTA before travel, no extensions

The programme is open to citizens of the participating countries only — it goes by nationality, not by residence, so living in a member country doesn't qualify you if you hold another passport. You also need an e-passport and must arrive on an airline or cruise line signed up to the scheme.

It covers the same ground as a visitor visa:

• Business — meetings, conferences, negotiations, contract work for a foreign employer.
• Tourism — holidays, visiting family and friends, medical treatment.

It doesn't permit working for a US employer, studying toward a degree, or journalism.

The trade is convenience for rigidity. You skip the visa interview and the fee, and in exchange you give up almost every flexibility a visa holder has. The 90 days cannot be extended, whatever the reason. You generally cannot change to another status from inside the US, and cannot adjust to permanent residence — with a narrow exception for immediate relatives of US citizens. Entering under the programme also waives your right to contest a removal decision, other than by claiming asylum.

An ESTA is the pre-travel authorisation itself. It permits you to board a carrier and request admission — as with any US entry, admission is the border officer's decision, and your actual permitted stay is recorded on your I-94.

• Eligibility is narrower than the country list suggests. Having travelled to a short list of designated countries since March 2011 — or to Cuba since January 2021 — disqualifies you, as does holding dual nationality with a handful of specified countries. A visa is then the only route in.
• An emergency buys a departure window, not a longer stay. If something genuinely stops you leaving on time, the authorities can grant a discretionary satisfactory departure period of up to 30 days. It only lets you leave without an overstay on your record.
• A pattern of back-to-back 90-day stays gets read as living in the US. There is no fixed required gap between visits, but officers assess whether you're visiting or effectively residing, and refusal at the border is the usual outcome once it looks like the latter.
• An approved ESTA is not a guarantee of entry. It permits boarding and a request for admission. The officer can still refuse, and refusal under the programme carries very limited rights of review.
• Changing passports invalidates the ESTA. A new passport, or a change of name or nationality, means a new ESTA — the authorisation is tied to the specific passport.
• A previous overstay usually ends your access to the programme. Once you've overstayed under the Visa Waiver Program, future visits generally require applying for a visa instead.

Overstaying costs you the programme itself: you become ineligible to use the Visa Waiver Program again and must apply for a visa for every future trip. The standard unlawful-presence bars apply on top — more than 180 days triggers a 3-year bar on returning, and a year or more triggers a 10-year bar. Because you waived the right to contest removal when you entered, there is also far less you can do if removal proceedings begin. Professional advice is strongly recommended in situations like this.

A straightforward two-week trip

You apply for an ESTA a week before flying, are approved, and spend 12 days in the US on holiday. You're far inside the 90 days, and the same ESTA covers further trips for the next 2 years.

A side trip that doesn't buy more time

You're admitted for 90 days, spend 70 in the US, then take a 10-day trip to Mexico expecting a fresh 90 on return. You're readmitted for the remainder instead, and the Mexican days may count too — leaving days rather than months.

A stay that can't be extended

At day 80 you're offered a longer contract and want another two months. You aren't eligible to apply for an extension or a change of status from inside the country, so the only lawful option is to leave before day 90.

• US Customs and Border Protection — Electronic System for Travel Authorization (ESTA)
• US Department of State — Visa Waiver Program
• US Customs and Border Protection — I-94 official website